Expression of protein zero is increased in lesioned axon pathways in the central nervous system of adult zebrafish

Abstract

The immunoglobulin superfamily molecule protein zero (P0) is important for myelin formation and may also play a role in adult axon regeneration, since it promotes neurite outgrowth in vitro. Moreover, it is expressed in the regenerating central nervous system (CNS) of fish, but not in the nonregenerating CNS of mammals. We identified a P0 homolog in zebrafish. Cell type-specific expression of P0 begins in the ventromedial hindbrain and the optic chiasm at 3-5 days of development. Later (at 4 weeks) expression has spread throughout the optic system and spinal cord. This is consistent with a role for P0 in CNS myelination during development. In the adult CNS, glial cells constitutively express P0 mRNA. After an optic nerve crush, expression is increased within 2 days in the entire optic pathway. Expression peaks at 1 to 2 months and remains elevated for at least 6 months postlesion. After enucleation, P0 mRNA expression is also upregulated but fails to reach the high levels observed in crush-lesioned animals at 4 weeks postlesion. Spinal cord transection leads to increased expression of P0 mRNA in the spinal cord caudal to the lesion site. The glial upregulation of P0 mRNA expression after a lesion of the adult zebrafish CNS suggests roles for P0 in promoting axon regeneration and remyelination after injury.

An Element in the α1-Tubulin Promoter Is Necessary for Retinal Expression during Optic Nerve Regeneration But Not after Eye Injury in the Adult Zebrafish

“…A first possibility is that the WT promoter is lacking some elements repressing promoter activity in this particular glial cell type. A second more interesting possibility is that, as reported for other proteins (Ankerhold et al, 1998;Bernhardt, 1999;Liu et al, 2002;Schweitzer et al, 2003), ␣1-tubulin is upregulated in a subset of non-neuronal cells in response to optic nerve lesion.…”

Schwann-cell cylinders grown inside hyaluronic-acid tubular scaffolds with gradient porosity

“…Although the SCs p0 expression has been formerly considered inherent to axonal signaling [85], its expression has been proved to be constitutive for SCs under certain conditions even in absence of axons [86]. A significant increase in p0 may support the effective regeneration of nervous tracts after lesions [87]. Thus, the p0 synthesis stimulation might represent an additional benefit of the present conduits for axonal pathway regeneration.…”

Fgf-Dependent Glial Cell Bridges Facilitate Spinal Cord Regeneration in Zebrafish

“…In adult zebrafish, glial scarring is not associated with brain injury models (Zupanc and Clint, 2001) and fish glia can actively support both fish and mammalian nerve regeneration (Bastmeyer et al, 1993;Bernhardt et al, 1996;Schweitzer et al, 2003;Zukor et al, 2011). Collectively, this raises the possibility that differential regulation of glia behavior contributes to the regenerative capacity of the teleost CNS, in addition to the intrinsic property of regenerating axons themselves.…”